1. Field of the Invention
This invention is in the field of self-locking threaded fasteners and relates more particularly to such a threaded fastener and tool combination for facilitating the manipulation thereof.
2. Description of the Prior Art
Locking bolt and nut assemblies wherein the bolt shank is in two parts which are relatively rotatable to provide free turning between the bolt and the nut in a tightening direction but to lock against untightening have long been known in the art. The art is exemplified by the devices in the following U.S. Pat. Nos. 514,570; 514,571; 537,244; 764,591 and 830,589.
In U.S. Pat. No. 514,571, the shank parts have an off-center cam so that for an untightening of the nut, one shank part will be forced radially outwardly against the nut threads causing the threads of that one part to bite into the nut threads to lock the bolt and nut against further tightening.
Further, various implements have been used to restrain the outward radial movement of the one shank part during the untightening rotation so that the nut may be removed from the bolt. One such implement is a thin, elongated stem longitudinally insertable between the shank parts to prevent the relative rotational movement and the outward radial movement of a shank part. However, even though the above devices have been known for many years, they have not found general use.